feat(discord): enable session join leave buttons

Move neutral join/leave handlers into GmRelay.Shared so Telegram and Discord share capacity, waitlist, duplicate-click, and schedule-update behavior.

Add Discord component routing for join_session and leave_session buttons with deferred ephemeral replies and serialized schedule message updates.

Bump version to 2.5.0 and update Discord docs.

Refs #29

src/GmRelay.Shared/packages.lock.json

@@ -2,11 +2,40 @@
   "version": 1,
   "dependencies": {
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+      },
+      "Microsoft.Extensions.Logging.Abstractions": {
+        "type": "Direct",
+        "requested": "[10.0.5, )",
+        "resolved": "10.0.5",
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+        "dependencies": {
+          "Microsoft.Extensions.DependencyInjection.Abstractions": "10.0.5"
+        }
+      },
+      "Npgsql": {
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+        "requested": "[10.0.2, )",
+        "resolved": "10.0.2",
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+        "dependencies": {
+          "Microsoft.Extensions.Logging.Abstractions": "10.0.0"
+        }
+      },
       "SecurityCodeScan.VS2019": {
         "type": "Direct",
         "requested": "[5.6.7, )",
         "resolved": "5.6.7",
         "contentHash": "WIE9RJswdSc2j+rLz2gW6U+gMUjMHzY2j7C/CL8/R2olXNM/+twarfMnWqm+rZodDBvaYDApJyxM8mVYf9FGrQ=="
+      },
+      "Microsoft.Extensions.DependencyInjection.Abstractions": {
+        "type": "Transitive",
+        "resolved": "10.0.5",
+        "contentHash": "iVMtq9eRvzyhx8949EGT0OCYJfXi737SbRVzWXE5GrOgGj5AaZ9eUuxA/BSUfmOMALKn/g8KfFaNQw0eiB3lyA=="
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